Investigating Changes in Real-time Conscious Postural Processing by Older Adults during Different Stance Positions Using Electroencephalography Coherence.

Background/Study Context: Adjustments of posture in response to balance challenges may lead to subsequent increases in conscious posture processing. If cognitive resources are stretched by conscious processing of postural responses fewer resources will be available to attend to environmental trip or fall hazards. The objective of the study was to explore brain activity related to conscious processing of posture as a function of movement specific reinvestment and fear of falling. Method: Forty-three older adults (M = 71.4, SD = 4.1) stood with a wide or narrow stance on a force-plate while neural coherence between verbal-analytical (T3) and motor planning (Fz) regions of the brain was assessed using electroencephalography. The propensity for movement specific reinvestment was assessed using the Chinese version Movement Specific Reinvestment Scale (MSRS-C) and fear of falling was assessed using the Chinese version Fall Efficacy Scale International (FES-I[CH]). Results: Scores from the MSRS-C were negatively correlated with changes in T3-Fz coherence that occurred when participants shifted from wide to narrow stance. Together, MSRS-C and FES-I(CH) uniquely predicted the percentage change in T3-Fz coherence between the two stance conditions. Conclusion: Presented with two postural tasks of different complexities, participants with a lower propensity for conscious control of their movements (movement specific reinvestment) exhibited larger changes in real-time brain activity (neural coherence) associated with conscious postural processing.

Gait Stability in Older Adults During Level-Ground Walking: The Attentional Focus Approach.

OBJECTIVES: The objective of this study was to investigate the effect of attentional focus instructions on gait stability during level-ground walking among older adults. METHODS: We recruited 140 community-dwelling older adults (mean age = 70.3 years, SD = 4.7 years) from elderly community centers in Hong Kong. The experiment included assessments on participant's characteristics and walking trials. During walking trials, each participant was invited to walk at a self-selected pace along a 6-m walkway. Internal focus instructions (Internal condition), external focus instructions (External condition), or no instruction (Control condition) were given in a randomized order for three trials per condition, giving a total of nine walking trials. Spatial and temporal gait parameters were measured. RESULTS: Results showed significantly higher body sway and variability of swing and stance time under Internal condition relative to External and Control conditions. Moreover, reduced velocity and shorter steps were demonstrated under Internal condition relative to External and Control conditions. DISCUSSION: External focus instructions did not improve gait stability in older adults when compared to Control condition. Internal focus instructions appear to compromise gait stability. Future research should investigate if walking instructions that refer to body movements explicitly compromise gait rehabilitation for older adults in clinical settings.

Effects of Shoe Top Visual Patterns on Shoe Wearers' Width Perception and Dynamic Stability.

Visual illusions caused by varied orientations of visual patterns may influence the perception of space and size, possibly affecting body stability during locomotion. This study examined the effect of variations in shoe top visual patterns on perception and biomechanical stability while walking and running. Twenty healthy adults performed five walking and running trials along an instrumented walkway when wearing shoes with five different striped patterns (plain, vertical, outward, horizontal, and inward). Before these locomotion trials, participants ranked their perceptions of shoe width. We used synchronized force platform and motion capturing systems to measure ground reaction force, mediolateral center of position displacement, ankle inversion and eversion, ankle excursion, and maximum eversion velocity. We rated stability perception on a 150-mm visual analog scale immediately after each shoe condition. Data analyses indicated that participants perceived plain and horizontal striped shoes as significantly wider than inward and vertical patterned shoes. During walking, participants wearing shoes with plain and horizontal striped patterns demonstrated smaller mediolateral center of position displacement, maximum eversion velocity, and ankle range of motion when compared with walking when wearing outward and vertical striped patterns; when running, we observed a similar effect for maximum eversion velocity. Thus, certain visual patterns on the tops of shoes influence the wearers' width perception and locomotion in ways that affect ankle stability during walking and running, with implications for risk of injury.